#16969 has been resolved on the assumption that PostgreSQL users always have access to the postgres database (read https://code.djangoproject.com/ticket/16969#comment:4).
Now either the bug is on Heroku's side and they should grant at least the CONNECT privilege to all of their users, or we decide that our assumption was wrong and we should at least partially revert our patch, or find a workaround. Thoughts?